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Numerous excellent resources have been published on the subject of water for coffee. Many authoritative sources, such as the Specialty Coffee Association (SCA) and the University of California, Davis Coffee Research Center, along with private sources, have already provided comprehensive insights into how water influences coffee brewing.
Instead of delving into exhaustive details about various aspects of water’s impact on coffee brewing, we will provide an overview of key concepts and offer links to websites where you can explore these valuable sources for more in-depth information if you wish to understand the science behind what makes great coffee.
The SCA and many coffee research centers have studied how minerals in water affect the extraction of flavor from coffee beans. They generally agree on four basic profiles that influence coffee flavor, depending on the mineral and alkalinity (carbonate) content of the water (refer to the chart below.)
The positive ions of calcium and magnesium attract the flavor molecules of coffee and extract the flavor from the bean. Since these flavor molecules are acidic, they can make the coffee taste sour unless there is sufficient alkalinity (in the form of bicarbonate) to buffer them. Bicarbonate reacts with the flavor molecules to release CO2 and provide the coffee with a smooth, rich taste. This combination of acidity and alkalinity is what gives espresso coffee its “crema,” the smooth texture that enhances its taste. Therefore, the balance of minerals and alkalinity is crucial for achieving the proper taste balance.
The mineral content required for making water suitable for making good coffee is not some industry-patented secret. It is in the public domain, and formulas for creating your own coffee water are available on various websites. However, the mineral content chosen by these websites varies according to personal preference, so even experts have slightly different preferences for the mineral content of their water when brewing coffee.
This chart shows a range of mineral and bicarbonate concentrations commonly accepted for brewing good coffee. If you use water outside of this zone, it will result in coffee with an off taste.
Too high mineral content and too low alkalinity will produce a heavy, dull, sour taste.
Too high mineral content and too high alkalinity will yield a heavy, flat, chalky taste.
Low mineral content and low alkalinity will result in an empty, sharp, sour taste.
Low mineral content and high alkalinity will create an empty, flat, chalky taste.
COFFEE WATER falls approximately in the middle of the spectrum, assuring you that it is suitable for any brewing method to produce good coffee. If you wish, you can experiment with this chart by attempting slightly more concentrated or diluted solutions to determine which mineral content best aligns with your taste preferences. There’s no need to purchase multiple solutions for different brewing methods.
The Specialty Coffee Association (SCA) is an exceptional group of dedicated individuals committed to delivering the best coffee experience for everyone. Arguably, it stands as one of the most reliable sources for comprehensive information on coffee preparation. This nonprofit, membership-based organization represents thousands of coffee professionals, ranging from producers to baristas worldwide. It is built on the principles of openness, inclusivity, and the sharing of knowledge, all aimed at nurturing a global coffee community and supporting initiatives to ensure specialty coffee thrives as an equitable and sustainable industry throughout the entire value chain.
The official SCA specifications, as outlined in the SCA 2009 handbook, recommend a preferred water for coffee with a total hardness ranging from as low as 50 ppm up to 175 ppm, and an alkalinity level at or near 40 ppn. https://sca.coffee/heritage-coffee-standards
In 2019, I had the pleasure of meeting Matt Perger, the founder of Barista Hustle, at the Boston Coffee Expo, where we discussed various formulas for creating coffee water. Barista Hustle stands out as one of the most straightforward websites that provide education on coffee brewing. They offer instructions on how to prepare concentrated solutions of baking soda and magnesium sulfate, which can later be measured and mixed with the desired amount of deionized or pure water when you’re ready to brew your coffee. https://baristahustle.com/blog/diy-water-recipes-the-world-in-two-bottles/
When water contains a high concentration of hardness, which typically includes calcium or magnesium, and is heated in coffee or espresso machines, this hardness combines with the carbonate alkalinity present in the water. This combination results in the precipitation of minerals, forming scale within the machine.
Conversely, if the mineral and alkalinity levels in the water are too low, carbon dioxide from the air dissolves into the water, creating carbonic acid. This acidic water can corrode your coffee equipment, potentially damaging it. To avoid this, it’s crucial to ensure there is enough alkalinity in the water to buffer the acidity.
Having a small amount of scaling in coffee equipment can actually be beneficial. It forms a protective coating inside the tank, preventing the pH from dropping to levels that could cause corrosion from carbonic acid to eat up your equipment. Therefore, striking the right balance between hardness minerals and carbonate alkalinity is essential for coffee equipment maintenance. The hardness should be low enough to prevent the constant headache of having to descale but high enough to prevent corrosion.
Magnesium is a preferable choice for water used in coffee equipment because it has a higher temperature-pressure and concentration-precipitation factor compared to calcium. This means that magnesium is less likely to precipitate out as easily as calcium at similar temperatures. If your water source has high calcium content, it can be addressed by using an RO (Reverse Osmosis) filter to remove excess calcium and adding the desired amount of magnesium for brewing.
For more information on how to properly maintain your coffee equipment, you can refer to the Coffee Technicians Guild at https://coffeetechniciansguild.org/.
For an in-depth article covering scaling, corrosion, and coffee machine care, “Jim Schulman’s Insanely Long Water FAQ” provides comprehensive insights on the topic. http://users.rcn.com/erics/Water%20Quality/Water%20FAQ.pdf
Fortunately, the formula that gives COFFEE WATER its great taste contains magnesium and calcium in concentrations low enough to minimize scaling, while the alkalinity level is sufficient to prevent corrosion.
All water will be somewhere on this spectrum. For coffee equipment, it is preferable to be on the slightly hard side, as it is much easier and cheaper to descale a machine than it is to replace the whole machine once it has been destroyed by corrosion.
Note: Other factors, apart from mineral and carbonate content, can influence the corrosiveness or scaling tendency of water. We have not included them in this chart because, by adding COFFEE WATER minerals to pure water, you can eliminate these other factors and accurately adjust the mineral content to be both safe for coffee machines and balanced for the best enhanced flavor of coffee.
We highly recommend the use of a Reverse Osmosis (RO) filter as the most cost-effective method to obtain pure and great-tasting water, which is essential for brewing the best coffee. When you opt for RO water, you can be confident that your water will be free from contaminants that might impart any unusual or undesirable tastes to your coffee.
Another viable option is using distilled water, which will yield similar results in terms of purity and taste. The only reason we haven’t suggested it as a home solution is due to the cost of having to purchase distilled water, or the considerable energy costs associated with home distillation systems, making them less practical.
De-ionization is another method for removing ions from water, but it is a more complex and technically involved process. It is not typically used for household purposes, especially with water that has a high mineral content, as the expense of replacing filters or de-ionizing resin can be significant. However, de-ionization can produce extremely pure water when used in conjunction with an RO filter.
Regardless of whether you choose RO, distilled, or de-ionized water, when you add COFFEE WATER minerals to it, you will achieve nearly identical results when brewing coffee.
KofeSolutions brings water filtration professionals and manufacturers together with coffee roasters and baristas to develop the best water solutions for achieving exceptionally great tasting coffee.
Our nearly two-year journey of research and development has been both exciting and enlightening. We were fortunate to have access to the Water Quality Laboratory at Puricom Water Industrial Corp. (https://www.puricom.com/en), where we conducted extensive testing using spectrometer analysis, as well as hardness and alkalinity titration analysis, to ensure precise mineral concentrations in our formulations.
Throughout this process, we tested a wide range of coffees from various origins, and experimented with a full spectrum of roast levels. We experimented with different mineral combinations and concentrations, meticulously documenting every nuance. Initially, most of our testing was conducted using the siphon brewing method to insure consistancy, but later on, we also conducted parallel experiments using pour-over, espresso, and various coffee machines.
In addition to scientific analysis, we drew upon the expertise of individuals with keen senses of taste and smell, such as my daughter, who is a wine and culinary connoisseur, and “Mr. Coffee,” our in-house roaster who has over forty years of experience roasting coffee. Their input was invaluable in our pursuit of excellence.
We sincerely hope that the dedication and effort we invested in developing COFFEE WATER will eliminate the guesswork for you and help you achieve consistently outstanding coffee results.
If you would like to know more about water quality, water filtration, or water for coffee, we welcome you to contact us. We also offer wholesale pricing.
COFFEE WATER mineral packs are available on Amazon.